GROSS ANATOMY

Detailed explanation-1: -The first set, called preganglionic neurons, originates in the brainstem or the spinal cord, and the second set, called ganglion cells or postganglionic neurons, lies outside the central nervous system in collections of nerve cells called autonomic ganglia.

Detailed explanation-2: -The neurotransmitters involved in the ANS are acetylcholine, norepinephrine, and epinephrine. Preganglionic neurons of the sympathetic and parasympathetic divisions and postganglionic neurons of the parasympathetic nervous system utilize acetylcholine (ACh).

Detailed explanation-3: -The postganglionic fibers that arise from the parasympathetic effector neurons are very short, and they are restricted to the visceral organs. Unlike the sympathetic nerves, parasympathetic fibers do not travel in spinal nerves to innervate other peripheral tissues.

Detailed explanation-4: -Parasympathetic ganglia which innervate targets in the head are located in four main ganglia: the ciliary, pterygopalatine, submandibular and otic ganglia. Scattered microganglia may also be distributed along cranial nerves.